Loans Receivable, Net - Credit Quality Indicators for RRE and Consumer Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Credit Quality Indicators By Origination
Total	$ 11,269,929	$ 11,122,696
Residential real estate
Credit Quality Indicators By Origination
Term loans originated current fiscal year	37,080	208,679
Term loans originated fiscal year before current fiscal year	220,196	181,924
Term loans originated two years before current fiscal year	133,625	100,273
Term loans originated three years before current fiscal year	83,079	76,394
Term loans originated four years before current fiscal year	65,036	53,819
Term loans originated five years before current fiscal year	203,795	179,085
Revolving loans	2,286	2,334
Total	745,097	802,508
Residential real estate | Performing
Credit Quality Indicators By Origination
Term loans originated current fiscal year	36,673	207,432
Term loans originated fiscal year before current fiscal year	219,651	179,915
Term loans originated two years before current fiscal year	133,269	99,135
Term loans originated three years before current fiscal year	82,095	75,527
Term loans originated four years before current fiscal year	64,227	52,905
Term loans originated five years before current fiscal year	197,805	174,281
Revolving loans	2,286	2,334
Total	736,006	791,529
Residential real estate | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	407	1,247
Term loans originated fiscal year before current fiscal year	545	2,009
Term loans originated two years before current fiscal year	356	556
Term loans originated three years before current fiscal year	750	867
Term loans originated four years before current fiscal year	809	87
Term loans originated five years before current fiscal year	2,760	1,876
Revolving loans	0	0
Total	5,627	6,642
Residential real estate | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	0	0
Term loans originated two years before current fiscal year	0	582
Term loans originated three years before current fiscal year	234	0
Term loans originated four years before current fiscal year	0	827
Term loans originated five years before current fiscal year	3,230	2,928
Revolving loans	0	0
Total	3,464	4,337
Home equity
Credit Quality Indicators By Origination
Term loans originated current fiscal year	18	89
Term loans originated fiscal year before current fiscal year	71	807
Term loans originated two years before current fiscal year	672	1,782
Term loans originated three years before current fiscal year	1,162	1,452
Term loans originated four years before current fiscal year	1,015	1,016
Term loans originated five years before current fiscal year	12,868	14,025
Revolving loans	609,563	617,234
Total	625,369	636,405
Home equity | Performing
Credit Quality Indicators By Origination
Term loans originated current fiscal year	18	89
Term loans originated fiscal year before current fiscal year	71	771
Term loans originated two years before current fiscal year	637	1,782
Term loans originated three years before current fiscal year	1,162	1,426
Term loans originated four years before current fiscal year	989	1,016
Term loans originated five years before current fiscal year	11,890	13,042
Revolving loans	606,083	612,545
Total	620,850	630,671
Home equity | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	0	0
Term loans originated two years before current fiscal year	0	0
Term loans originated three years before current fiscal year	0	26
Term loans originated four years before current fiscal year	0	0
Term loans originated five years before current fiscal year	520	463
Revolving loans	1,168	2,397
Total	1,688	2,886
Home equity | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	0
Term loans originated fiscal year before current fiscal year	0	36
Term loans originated two years before current fiscal year	35	0
Term loans originated three years before current fiscal year	0	0
Term loans originated four years before current fiscal year	26	0
Term loans originated five years before current fiscal year	458	520
Revolving loans	2,312	2,292
Total	2,831	2,848
Other consumer
Credit Quality Indicators By Origination
Term loans originated current fiscal year	48,670	131,302
Term loans originated fiscal year before current fiscal year	114,926	66,327
Term loans originated two years before current fiscal year	57,385	42,827
Term loans originated three years before current fiscal year	36,830	16,287
Term loans originated four years before current fiscal year	13,154	10,519
Term loans originated five years before current fiscal year	25,409	18,692
Revolving loans	27,804	27,117
Total	324,178	313,071
Other consumer | Performing
Credit Quality Indicators By Origination
Term loans originated current fiscal year	48,652	131,098
Term loans originated fiscal year before current fiscal year	114,701	65,921
Term loans originated two years before current fiscal year	56,947	42,557
Term loans originated three years before current fiscal year	36,469	16,202
Term loans originated four years before current fiscal year	13,093	10,409
Term loans originated five years before current fiscal year	24,347	17,334
Revolving loans	27,381	26,704
Total	321,590	310,225
Other consumer | 30-89 Days Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	0	158
Term loans originated fiscal year before current fiscal year	173	170
Term loans originated two years before current fiscal year	145	212
Term loans originated three years before current fiscal year	168	38
Term loans originated four years before current fiscal year	10	48
Term loans originated five years before current fiscal year	784	1,155
Revolving loans	21	411
Total	1,301	2,192
Other consumer | Non-Accrual and 90 Days or More Past Due
Credit Quality Indicators By Origination
Term loans originated current fiscal year	18	46
Term loans originated fiscal year before current fiscal year	52	236
Term loans originated two years before current fiscal year	293	58
Term loans originated three years before current fiscal year	193	47
Term loans originated four years before current fiscal year	51	62
Term loans originated five years before current fiscal year	278	203
Revolving loans	402	2
Total	$ 1,287	$ 654